1. Field of the Invention
This invention relates to thiadiazines and more particularly to new 1,3,4-thiadiazines having aromatic groups at the 2- and 4-positions and a 6-membered nitrogen-containing aromatic ring fused to the 5,6-positions. These new compounds are useful as dyes.
2. Prior Art
A fused-ring system containing the 1,3,4-thiadizine ring has been prepared by reaction of .alpha.-halo-benzaldehyde-2, 4-dihalogenophenylhydrazones and a thioacetate [Barnish, J. Chem. Soc. (C) 1970 854]. These have the structure: ##STR2## X being Br, Cl or F.
A purple compound having a phenylazo group in the 2-position, i.e., ##STR3## has been reported by McDonald, Chem. Communications 1969. 392. It was prepared from dithizone by oxidation.
Elliott (the applicant), McMaster University Thesis (1971), reacted dithizone with 2,3-dichloroquinozaline to give ##STR4## Reaction of dithizone with 2-chloro-3-nitropyridine gave the purple compound of the structure ##STR5## The azo compounds lack fluorescence and have poor dye quality.
Compounds having aromatic nuclei directly attached to both the 2- and 4-positions of a 1,3,4-thiadiazine ring have been reported, but the 5,6-positions were not attached to a heterocyclic aromatic ring.